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-   -   Lamda 2 criterion for vortex identification (https://www.cfd-online.com/Forums/fluent/42525-lamda-2-criterion-vortex-identification.html)

 Aindya October 10, 2006 22:15

Lamda 2 criterion for vortex identification

How can I calculate the Lambda 2 criterion for vortex identification in Fluent? I am studying the flow over a bluff body using LES.

Anindya

 sarah_ron October 11, 2006 13:23

Re: Lamda 2 criterion for vortex identification

I think you could do it by UDF or custom defined function.

 m-k June 4, 2011 12:34

Hi, could anyone please write a step-by-step way to calculate lambda 2 in Fluent, Tecplot or Paraview?
Cheers

 Trev June 6, 2011 11:55

You can easily extract vortex cores in Tecplot which should show you what large scale coherent structures are present in the flow. I can't remember how its done as there are 2 methods to calculate it but either way you are going to get something relatively similar to what the lambda-2 criterion would calculate.

I know under tools there is an option for the tensor eigensystem (once you've edited the .add file). Found this link for it which fortunately describes it use for calculating the lambda-2 criterion.

If you are looking for coherent structures in the flow you could possibly think about doing a POD analysis for the first few modes if you have enough data. As I've found this to be great for extracting underlying flow structures which I wouldn't of otherwise known about.

Neil

 m-k June 7, 2011 03:51

Hi Neil! Thank you for your quick reply. I found it. The Contours issue of Tecplot on how to calculate lambda 2 is not available any more online.. Instead the calculation is described in Tecplot's user's manual (http://download.tecplot.com/360/tpum.pdf).

Cheers, :)

 yhy20081016 April 3, 2017 22:39

You can use the ANSYS CFD-Post.

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